Concept: This question tests your understanding of the structural organization of the Central Nervous System (CNS), specifically the composition of its grey and white matter.

Why (C) is correct:

In the CNS, myelinated nerve fibers (axons covered by a myelin sheath) are responsible for the rapid transmission of nerve impulses. The myelin sheath, rich in lipids, gives these areas a whitish appearance, hence they form the white matter. Conversely, non-myelinated nerve fibers, along with neuron cell bodies, dendrites, and synapses, constitute the grey matter. These areas are involved in processing information.

Why other options are wrong:

• A) Grey matter, white matter: This is the reverse of the correct composition.
• B) Ependymal cells, neurosecretory cells: These are types of cells found in the CNS but do not define grey or white matter based on myelination. Ependymal cells line ventricles, and neurosecretory cells produce hormones.
• D) Neurosecretory cells, Ependymal cells: Incorrect cell types for defining grey/white matter.

Common Mistake: Students often confuse which type of fiber (myelinated vs. non-myelinated) corresponds to which matter (grey vs. white).

NEET Tip: Remember 'White Matter = Myelinated' (WMM) and 'Grey Matter = Cell Bodies' (GMCB). The myelin sheath is fatty and appears white.

Correct Answer: (C)